2009 Yamaha YZ125Y/YZ125 Owner's Service & Repair Manual (P/N LIT-11626-22-54)

This 2009 Yamaha YZ125Y Owner's Service Manual, publication LIT-11626-22-54 (cover code 1C3-28199-14), covers operation, maintenance, repair, and tuning, including the regional YZ125 versions.

• Engine and transmission: Cylinder, piston, and crankshaft inspection; crankcase separation; clutch repair; kick shaft and shift shaft service; shift cam and shift fork assembly.

• Fuel and exhaust: Mikuni carburetor disassembly and fuel-level adjustment, reed valve inspection, power valve and YPVS governor service, and silencer packing replacement.

• Cooling system: Radiator removal, radiator-cap pressure checks, cooling-system leak testing, and water-pump shaft, bearing, and seal replacement.

• Brakes and chassis: Hydraulic brake bleeding, caliper and master-cylinder repair, wheel-bearing replacement, steering-head service, and swingarm linkage inspection.

• Suspension and tuning: Front-fork overhaul, rear-shock spring and bearing work, damping adjustments, spring-selection tables, and symptom-based suspension setting charts.

• Electrical diagnosis: CDI magneto removal, ignition-timing checks, a no-spark troubleshooting chart, wiring and connector diagrams, and ignition-coil and stator resistance tests.

The manual combines owner maintenance guidance with engine, chassis, and electrical chapters expressly intended for people with Yamaha motorcycle servicing knowledge and skills.

Model Codes and Regional Settings

Model codes identify 1C3H for the US and Canada, 1C3J for Europe, and 1C3L for Australia, New Zealand, and South Africa. The European and South African versions are designated YZ125. Carburetor specifications and suspension settings distinguish the applicable markets; rear-shock spring identification also accounts for production-lot differences.

Engine, Clutch, and Internal Repair

Top-end coverage includes cylinder-wear measurements, piston-ring inspection, and the A–D cylinder/piston matching chart. The chart connects cylinder markings with color-coded piston sizes, helping you identify the matching replacement before ordering. The cylinder instructions expressly prohibit reboring.

Bottom-end procedures cover crankshaft removal and installation, gearbox inspection, and shift-fork orientation. Preparation notes address keeping wear-matched components together during disassembly. Exploded assembly views and job instruction charts identify component order and assembly notes.

Tool references include crankcase separator YU-1135-A/90890-01135 and clutch holding tool YM-91042/90890-04086.

Carburetor, Cooling, and Race Setup

Jetting information distinguishes the 6BFY42-74 needle for US/Canadian models from the 6BFY43-74 needle for the other listed markets. The venturi block and fixed main nozzle are not intended for disassembly; disturbing them can reduce carburetor performance.

Atmospheric-condition tables, throttle-opening diagrams, and symptom-based carburetor setting charts relate jetting changes to track conditions. Test runs and spark-plug checks remain part of evaluating those settings.

Cooling coverage includes separate radiator-cap and system-pressure tests, plus inspection criteria for water-pump leakage.

Brake and Suspension Service

Brake sections cover piston and seal inspection, master-cylinder cup orientation, hose routing, and bleeding. Race-based maintenance charts accompany the repair chapters.

Fork coverage includes damper bleeding, oil-seal replacement, and assembly checks. Yamaha recommends dealer maintenance for the fork and warns that dropping the damper assembly into the inner tube can damage its internal valve.

Rear-shock work covers removal, installation, spring replacement, and mounting-bearing service. Internal shock-cylinder and nitrogen-reservoir overhaul is outside this coverage; Yamaha warns against opening these pressurized components. Separate front-fork and rear-shock setting charts address symptoms such as harshness, bottoming, and poor traction.

Follow the manual's safety guidance for hydraulic brakes and pressurized suspension components, and consult a qualified technician when a procedure exceeds your experience.

A Preview of Torque, Wear Limits, and Ignition Test Data

These examples are a small selection of the manual's service data. Torque tables list cylinder-head nuts at 28 Nm and the spark plug at 20 Nm; the brake sections specify 6 Nm for caliper bleed screws and DOT #4 brake fluid.

Wear checks include a 1.2 mm limit for installed piston-ring end gap and a 2.8 mm minimum clutch friction-plate thickness.

For ignition diagnosis, the CDI magneto pickup-coil specification is 248–372 ohms at 20°C, with the test connections identified in the electrical chapter.

PDF Navigation and Page Details

Search, bookmarks, and diagram detail: Service text is searchable, with chapter and section bookmarks. The warranty-page body and some drawing labels are outside the searchable text. Small wiring and connector labels are clear when enlarged; the separate “Table Of Contents” bookmark has no destination.

The download contains one printable, English-language, 231-page PDF: 217 chapter pages, 13 pages of front matter including the cover, warranty, and contents, and one memo page. All are included in the total.